Universal joint with a securing element

ABSTRACT

A universal joint includes two joint yokes that, respectively, have two yoke arms that each start from a connection portion. Through an eye portion distanced from the connection portion, bearing bores extend in which respectively, a journal of a journal cross by means of interposition of rolling members and of a bearing bushing are supported. On the outside of the yoke arms, a bulge is respectively provided towards the connection portion and adjacent to the bearing bore and over a partial circumference of the same, which bulge has, towards the bearing bore, a groove. A circumferential groove, belonging to a retaining trunnion projecting from the base of the bearing bushing, is arranged opposite to the groove. Between the two, a securing element is arranged that engages with an engagement portion in the groove and with a retaining portion facing away from the same, in the circumferential groove of the retaining trunnion. As the groove for receiving the securing element, which serves for the retainment of the bearing bushing in the bearing bore, is not designed to extend circumferentially fully around the bearing bore, the material thickness on the free end of the yoke arms can be reduced on the outside.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a universal joint with a securingelement that serves to secure a bearing bushing supporting a journalcross and that is received in a bearing bore of a yoke arm of a jointyoke.

[0002] German Patent No. 34 46 456 C1 describes an axial retainment of abearing bushing in a yoke eye of a joint yoke of a universal joint.Adjacent to the bearing bore, in an area of the same projecting to theoutside over the base of the bearing bushing, an annular grooveextending over the complete circumference is provided. On twodiametrically opposite positions of the eye portion, a groove isrespectively provided, into which a securing ring, formed incross-section as an angle ring with projections, can be inserted and canthen be turned for the retainment so that the projections engage in thegroove. The securing of the ring against rotation is then carried out bymeans of a grub screw. Thus, for the securing ring, a type of bayonetlocking is selected.

[0003] When articulating the joint yokes of a universal joint relativeto each other, the yoke arms of the one joint yoke engage mutually in agap between the yoke arms of the other joint yoke. The yoke arms of ajoint yoke are connected to a connection portion. The yoke arms projectfrom the connection portion of the joint yoke in an offset mannerrelative to the longitudinal axis. The free ends of the yoke arms dip,respectively, into the gap between the yoke arms of the other jointyoke. The larger the distance of the outer contour of the yoke arms inthe area of their ends distanced to the connection portion from thearticulation center of the joint, the larger is the rotational circlewhen articulating the two joint yokes to each other. Basically, it isnecessary especially for the universal-jointed shafts, designed for ahigh capacity of torque, to design the individual joint yokes of auniversal joint to be as compact as possible, i.e., to keep therotational diameter as small as possible.

[0004] Therefore, the invention has the object to provide a universaljoint that, when maintaining the capacity of articulation of the jointyokes of the universal joint to each other, is formed more compact,i.e., has a smaller rotational diameter.

SUMMARY OF THE INVENTION

[0005] The object is solved according to the invention by a universaljoint having two joint yokes respectively centered on a longitudinalaxis and having, respectively, a connection portion, having,respectively, two yoke arms, starting, respectively, from the connectionportion and which end, respectively, in an eye portion, distanced to theconnection portion and off-set from the longitudinal axis in oppositedirections, and having, respectively, a through extending bearing bore,arranged at a right angle to the longitudinal axis on a bore axis, andwherein both yoke arms of at least one of the joint yokes are providedon the outside with a bulge on a partial circumference of the bearingbore towards the connection portion and arranged symmetrically to aparallel line to the longitudinal axis through the bore axis, whichbulge towards the bearing bore is provided with a groove, a journalcross, having four journals, arranged in pairs on a journal axis andwhich journal axes are arranged at a right angle to each other, bearingbushings, supporting the journals and respectively, received in abearing bore of one of the yoke arms, closed by a base and to which,respectively, a retaining element is arranged, and a securing elementfor each bearing bushing, having an engagement portion, engaging in thegroove of the bulge of the corresponding yoke arm, which, together withthe retaining element holds the bearing bushing axially in an unmovablemanner.

[0006] Of advantage in this embodiment is that in the area of the eyeportion of the yoke arms of a joint yoke, material can be saved, inwhich in a conventional design, a securing ring engages in a groove,i.e., which determines the rotational diameter when articulating thejoint yokes relative to each other. As the retainment can be arrangeddistanced to the free ends of the yoke arms, it is possible to achievein total a more compact design, i.e., to reduce the rotational diameterespecially under articulation so that no reduction of the torquecapacity occurs at the same angle of articulation as before. For this,as the ideal condition, it is aspired that the journal cross bearingdetermined layout-wise by the predetermined torque limits by means ofthe bearing bushings the rotational diameter, in that the joint yokesextend at their free ends with their outer contour offset towards thelongitudinal axis. Also, the width of the bulge can be designed such,that the rotational diameter is not negatively influenced.

[0007] The retaining element can diversely be formed for the retainmentof the bearing bushing in connection with the securing element and thegroove in the bulge.

[0008] Preferably, it is provided that the groove is formed,respectively, as a circular arc groove, centered on the bore axis or onan axis parallel thereto.

[0009] Alternatively, it is provided that the groove is formed straightand intersects the parallel line at a right angle.

[0010] A first embodiment of the retainment provides that the retainingelement comprises a retaining trunnion projecting from the base of thebearing bushing to the outside and centered on the bore axis and theretaining trunnion having a circumferential groove. In this case, thecircumferential groove can be arranged concentrically to the circulararc groove. A further embodiment provides that the retaining elementcomprises a head screw and a threaded bore in the base of the bearingbushing, and that the securing element comprises a through bore for thehead screw and comprises the engagement portion, engaging in the grooveof the bulge.

[0011] A first embodiment of the securing element provides that thesecuring element comprises a through bore through which the retainingtrunnion extends, wherein the securing element is retained by a securingring, engaging in the circumferential groove of the retaining trunnionand engaging with its engaging portion in the groove of the bulge.Preferably, it is provided for the circular arc groove that it extendsover an arc of approximately 90° in reference to the bore axis of thebearing bore. In this area, the rotational diameter is not influenced bythe size of the bearing bushing. Furthermore, the support in this areais sufficient for taking up the axial forces.

[0012] A further embodiment of the securing element provides that thesecuring element is formed like an annulus. In this case, it ispreferably provided that the securing element comprises an arc portion,forming the arc-like engagement portion and which engages in the grooveof the bulge formed as a circular arc groove, comprises at least oneretaining portion engaging in the circumferential groove of theretaining trunnion and comprises the connection portions connecting theend(s) of the retaining portion(s) to the ends of the arc portion.

[0013] In a first design variant of this securing element, a continuousretaining portion is provided so that the arc portion, the connectionportions, and the retaining portion are continuous with each other.

[0014] The retaining portion and the arc portion are formed to deformelastically towards each other and are respectively provided with aneyelet for the engagement by a tool. This tool can, for example, beformed similar to a collet chuck for spring rings. In this case, it canbe provided that the arc portion and the retaining portion(s) arearranged in one plane, or in planes offset to each other, and arearranged distanced to each other elastically movable towards each other.

[0015] A second embodiment for the securing element provides that tworetaining portions are provided wherein, on the free ends of theretaining portions, an eyelet for the engagement by a tool is provided,respectively.

[0016] Various objects and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of the preferred embodiments, when read in light of theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a side view of a universal joint shaft, half in view andhalf in section, wherein the universal joints are shown in alignedposition.

[0018]FIG. 2 is an enlarged sectional view taken along line II-II ofFIG. 1.

[0019]FIG. 3 is a further enlarged top plan of the eye portion of oneyoke arm illustrated in FIGS. 1 and 2 showing a first embodiment of asecuring element.

[0020]FIG. 4 is a sectional view taken along line IV-IV of FIG. 3.

[0021]FIG. 5 is an enlarged top plan view similar to FIG. 3 of a secondembodiment of a securing element.

[0022]FIG. 6 is an enlarged top plan view similar to FIG. 3 of a thirdembodiment of a securing element.

[0023]FIG. 7 is a sectional view taken along line VII-VII of FIG. 6.

[0024]FIG. 8 is an enlarged top plan view similar to FIG. 3 of a fourthembodiment of a securing element.

[0025]FIG. 9 is a sectional view taken along line VIII-VIII of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026]FIG. 1 shows a universal joint shaft having a first universaljoint 1 and a second universal joint 2, as well as a telescopicarrangement 4 between the two universal joints 1 and 2 that enables achange of position of the same along a longitudinal axis 3. FIG. 2 showsa sectional view of FIG. 1 in an enlarged scale. The universal joints 1and 2 are shown in the aligned position, i.e. at an articulation angleof 0°. Thus, all of the components are aligned on the longitudinal axis3.

[0027] As, in principal, the same design is given for the two universaljoints 1 and 2, with the exception of their connections to thetelescopic arrangement 4, a description of the invention is given bymeans of the first universal joint 1. The first universal joint 1consists of a first joint yoke 5 and a second joint yoke 6. The firstjoint yoke 5 has a connection portion 9 from which two yoke arms extend,namely, a first yoke arm 7 and the second yoke arm 8. The two yoke arms7 and 8 are arranged distanced to the longitudinal axis 3, i.e., theyare diametrically offset from this longitudinal axis 3 in oppositedirections. Each of the two yoke arms 7 and 8 has an eye portion 10 onthe end distanced from the connection portion 9. The eye portions 10have a bearing bore 11 that extends at a right angle to the longitudinalaxis 3; The bearing bores 11 of the two yoke arms 7 and 8 are arrangedon a common bore axis 16, as best shown in FIG. 2. It is also visiblefrom FIG. 2 that in the bearing bores 11 with the bore axis 16, twojournals 13 of a journal cross 12 (having a total of four journals 13)are received. The axes of the four journals 13 are arranged in oneplane. The journals 13 extend at right angles relative to each other.

[0028] The support of the journal cross 12 in the bearing bore 11 isachieved by means of bearing bushings 14 that, by means of interpositionof rolling members 15, are rotatably supported on respective trunnions13. The bearing bushings 14 are, on one side, closed by a base 17.

[0029] The design of the second joint yoke 6 corresponds essentially tothe design of the first joint yoke 5 with exception of the connections.While the first joint yoke 5 is connected to a stub shaft of thetelescopic arrangement 4, the second joint yoke 6 has a flange. Theuniversal joint shaft serves for the transmission of a torque and isdesigned for high torques. Such high capacity universal shafts are, forexample, used in drives of rolling mills.

[0030] By means of FIGS. 3 to 9, a detailed description of the differentembodiments for the securing of the bearing bushing 14 in the bearingbore 11 is given, by means of which it will be obvious that a morecompact design can be achieved. The arrangement described in thefollowing in reference to the first yoke arm 5 is also applicable to thefurther supports.

[0031] Firstly, a first embodiment (which is also shown in FIGS. 1 and2) is described in more detail by means of FIGS. 3 and 4. In the bearingbore 11 formed in the eye portion 10 of the first yoke arm 7, a bearingbushing 14 is received. In the bearing bushing 14, a journal 13 issupported by interposition of rolling members 15. The bore axis 16 shownin FIG. 4 corresponds to the journal axis of the journals 13.Furthermore, the longitudinal axis 3 is shown in FIG. 4. At theintersection point of the bore axis 16 with the longitudinal axis 3, thecenter of articulation of the first universal joint 1 is arranged. Inthe eye portion 10 of the first yoke arm 7, a bulge 19 is formed thatextends over a partial circumference TU of the bearing bore 11 adjacentto the connection portion 9 on the outside of the yoke arm 7. The bulge19 has, facing toward the bearing bore 11, a circular arc groove 20formed therein. The center of this circular arc groove 20 is centered onthe bore axis 16 in this embodiment. The bulge 19 is formedsymmetrically in reference to a line 18 that extends parallel to thelongitudinal axis 3 through the bore axis 16. In other words, the angleformed by the partial circumference TU in reference to the bore axis 16(90°, for example) is halved by the parallel line 18. Alternatively, thegroove 20 may extend in a straight line that intersects the line 18 at aright angle.

[0032] The circular arc groove 20 is limited at the circumferential endsby abutments 21. A retaining trunnion 22 (forming a retaining element)is projectingly formed on the outside on the base 17 of the bearingbushing 14. This retaining trunnion 22 is centered on the bore axis 16and has a circumferential groove 23 formed therein that is arrangedopposite to the circular arc groove 20 when the bearing bushing 14 isinstalled within the bearing bore 11 of the yoke arm 7. The base 17 ofthe bearing bushing 14, which is arranged next to the retaining trunnion22 thereon, is located in the area of the bearing bore 11 of the firstyoke arm 7, distanced from the connection portion 9 and slightly outsideof the radially outer dimensions of the eye portion 10, which is visibleby the represented rotational radius R, i.e., the rotational circleinscribed by the same. It can be seen that the largest radial dimensionsare arranged in the area of the bore axis 16.

[0033] A securing element 24 is provided for retaining the bearingbushing 14 within eye portion 10 of the yoke arm 7. The securing element24 includes an arc portion 26 having a front edge that forms anengagement portion 25. The engagement portion 25 extends within thecircular arc groove 20 formed in the bulge 19. A securing element 24also includes a retaining portion 27 that extends within thecircumferential groove 23 formed in bearing bushing 14. A pair ofconnection portions 28 follow the two ends of the arc portion 26 andconnect the retaining portion 27 to the arc portion 26. The arc portion26 and the retaining portion 27 can be elastically moved relatively toother. If desired, one or more eyelets 29 can be provided on thesecuring element 24, such as on the arc portion 26 and the retainingportion 27, as illustrated. The eyelets 29 can serve, for example, tofacilitate the engagement of a collet chuck that can be used to assistin the mounting or detachment of the securing element 24. So that thesecuring element 24 cannot be displaced in circumferential directionaround the bore axis 16 in the circular arc groove 20 and thecircumferential groove 22 and thus can be brought out off contact to thesame, the circular arc groove 20 is closed at the ends in reference toits partial circumference by the abutments 21. The abutments 21 can beproduced, for example, after the manufacture of the circular arc groove20 and the first mounting of a securing element 24 by deforming theouter portions of the bulge 19 above the circular arc groove 20.

[0034] Alternatively, it is possible to offset the center point of thecircumferential groove 23 and the center point of the circular arcgroove 20 relative to each other. For example, the center point of thecircular arc groove 20 may be not arranged on the bore axis 16, but maybe arranged offset from the same in direction away from the bulge 19.

[0035]FIG. 5 shows a second embodiment for a securing element 124 thatis changed in reference to FIGS. 3 and 4 in such a way that acontinuously closed annular design is not provided in the securingelement 24, as described above. Rather, in a modified securing element124, two retaining portions 127 are connected via respective connectionportions 128 to the ends of an arc portion 126, forming the engagementportion 125. On the ends of the two retaining portions 127, eyelets 129are provided for the engagement of a tool, as described above. Thedesign of the retaining trunnion 22 with the circumferential groove 23on the bearing bushing 14 corresponds to the design described inconnection with FIGS. 3 and 4. The securing of the securing element 124is also achieved by the abutments 21 provided on the ends of thecircular arc groove 20 formed in the bulge 19 in the same manner asdescribed above.

[0036] For the securing elements 24, 124, and also for the laterdescribed further securing elements 224, 324, the thicknesses thereofcan be selected such, as it is common in connection with securing ringsfor the assembly of bearing bushings in journal crosses, to produce thenecessary or desired clearances.

[0037] In a third embodiment illustrated in FIGS. 6 and 7, the outeredge portion of a securing element 224 formed, for example, from sheetmetal extends within the circular arc groove 20 formed in the bulge 19and serves as an engagement portion 225, entering the circular arcgroove 20. At the end facing away from this engagement portion 225, thesecuring element 224 has a bore 32 formed therethrough, through which ahead screw 30 is screwed into a threaded bore 31 in a base 217 of amodified bearing bushing 214. In circumferential direction around thebore axis 16, the rotational retainment for the securing element 224 canbe achieved by abutments in the area of the circular arc groove 20,similar to those described above in connection with FIGS. 3, 4, and 5.

[0038] In a fourth embodiment illustrated in FIGS. 8 and 9, a securingelement 324 is provided that corresponds essentially to the securingelement 224 described in connection with the bearing bushing 214. Inthis embodiment, however, the securing element 324 also has a bore 33formed therethrough. The outer edge portion of the securing element 324forms the engagement portion 325 that extends within the circular arcgroove 20 of the bulge 19. Similar to the embodiment according to FIGS.3 to 5, a bearing bushing 314 is provided with a retaining trunnion 322.The retaining trunnion 322 has also a circumferential groove 323 formedtherein. The circumferential groove 323 does, however, not serve for theengagement of the securing element 224. Rather, in this embodiment, thesecuring element 324 is only retained by means of the through bore 33formed in the retaining trunnion 322 and is secured thereto by asecuring ring 34 that extends within the circumferential groove 323.

[0039] In all of the embodiments, it is common that the bulge 19 onlyextends over a partial circumference TU of the bearing bore 11, and thebulge 19 is arranged in a circumferential portion of the bearing bore 11that is arranged on the outside near the connection portion 9, by whichthe two yoke arms 7, 8 of the joint yoke 5 are connected to each other,so that in the free end portion of the eye portion 10 of the yokes arm7, 8 in reference to the longitudinal axis 3, smaller dimensions areachieved, so that the rotational radius R, which the outer edges duringarticulation of the two joint yokes 5, 6 of the universal joint 1 carryout in reference to each other, is reduced, and therefore, as a whole, amore compact design at a given angle capacity is achieved. Areas areused for the axial retainment of the bearing bushing, which practicallydo not negatively influence the rotational diameter.

[0040] In accordance with the provisions of the patent statutes, theprinciple and mode of operation of this invention have been explainedand illustrated in its preferred embodiments. However, it must beunderstood that this invention may be practiced otherwise than asspecifically explained and illustrated without departing from its spiritor scope.

What is claimed is:
 1. A universal joint comprising: two joint yokesrespectively centered on a longitudinal axis, each of the joint yokesincluding a connection portion having, respectively, two yoke armsstarting from the connection portion and ending with respective eyeportions that are distanced to the connection portion and offset fromthe longitudinal axis in opposite directions, each of the yoke armshaving, respectively, a through extending bearing bore that is arrangedat a right angle to the longitudinal axis on a bore axis, and whereinboth yoke arms of at least one of the joint yokes are provided on theoutside with a bulge on a partial circumference of the bearing boretoward the connection portion and arranged symmetrically to a parallelline to the longitudinal axis through the bore axis, which bulge isprovided with a groove facing toward the bearing bore; a journal crosshaving four journals that are arranged in pairs on a journal axis anddefine journal axes that are arranged at a right angle to each other;bearing bushings supporting the journals and respectively received in abearing bore of one of the yoke arms, each of the bearing bushings beingclosed by a base to which, respectively, a retaining element isarranged; and a securing element for each bearing bushing having anengagement portion that extends within the groove of the bulge of thecorresponding yoke arm which, together with the retaining element, holdsthe bearing bushing axially in an unmovable manner.
 2. The universaljoint according to claim 1 characterized in that each of the grooves isformed as a circular arc groove centered on the bore axis or on an axisparallel thereto.
 3. The universal joint according to claim 1characterized in that each of the grooves is formed straight andintersects the parallel line that extends parallel to the longitudinalaxis at a right angle.
 4. The universal joint according to claim 1characterized in that each of the retaining elements includes aretaining trunnion that projects outwardly from the base of the bearingbushing and is centered on the bore axis, each of the retainingtrunnions having a circumferential groove formed therein.
 5. Theuniversal joint according to claim 1 characterized in that each of theretaining elements includes a head screw that is threaded into athreaded bore in the base of the bearing bushing, and wherein each ofthe securing elements includes a through bore, through which the headscrew passes, and an engagement portion that extends within the grooveof the bulge.
 6. The universal joint according to claim 4 characterizedin that each of the securing elements includes a through bore, throughwhich the retaining trunnion extends, and wherein each of the securingelements is retained on the retaining trunnion by a securing ring thatextends within the circumferential groove of the retaining trunnion andwithin the groove of the bulge.
 7. The universal joint according toclaim 1 characterized in that each of the securing elements includes anarc portion that forms an arc-like engagement portion that extendswithin the groove of the bulge formed as a circular arc groove, at leastone retaining portion that extends within the circumferential groove ofthe retaining trunnion, and at least one connection portion thatconnects the at least one retaining portion to the arc portion.
 8. Theuniversal joint according to claim 7 characterized in that each of thearc portions and each of the at least one retaining portions arearranged in one plane or in planes offset to each other, and further arearranged distanced to each other and are elastically deformable towardseach other.
 9. The universal joint according to claim 7 characterized inthat one continuous retaining portion is provided so that the arcportion, the connection portions, and the retaining portion arecontinuous with each other.
 10. The universal joint according to claim 9characterized in that the retaining portion and the arc portion are,respectively, provided with an eyelet for engagement by a tool.
 11. Theuniversal joint according to claim 7 having a securing element with tworetaining portions, wherein an eyelet for the engagement of a tool isprovided on free ends of each of the retaining portions.
 12. A yoke andjournal cross assembly for a universal joint comprising: a yokeincluding a connection portion that defines a longitudinal axis andfirst and second yoke arms that extend from the connection portion andend in respective eye portions that are distanced from the connectionportion and offset from the longitudinal axis in opposite directions,each of the eye portions having a bearing bore extending therethrough ata right angle to the longitudinal axis, each of the yoke arms beingprovided with respective bulges on partial circumferences of the bearingbores toward the connection portion that extend partially about thebearing bores, each of the bulges having a groove formed therein; ajournal cross having four journals that are arranged in opposed pairsthat define respective journal axes that are arranged at a right angleto one other; a pair of bearing bushings respectively supported on oneof the opposed pairs of journals of the journal cross and respectivelyreceived in the bearing bores of the yoke arms of the yoke, each of thebearing bushings being closed by a base having a retaining elementprovided thereon, and a pair of securing elements respectively retainingthe bearing bushings to the yoke arms of the yoke, each of the securingelements including an engagement portion that extends within the grooveformed in the bulge of the yoke arm and a retaining portion that engagesthe retaining element for retaining the bearing bushing in an axiallyunmovable manner relative to the yoke arms of the yoke.
 13. Theuniversal joint according to claim 12 characterized in that each of thegrooves is formed as a circular arc groove centered on the bore axis oron an axis parallel thereto.
 14. The universal joint according to claim1 characterized in that each of the retaining elements includes aretaining trunnion that projects outwardly from the base of the bearingbushing and is centered on the bore axis, each of the retainingtrunnions having a circumferential groove formed therein.
 15. Theuniversal joint according to claim 1 characterized in that each of theretaining elements includes a head screw that is threaded into athreaded bore in the base of the bearing bushing, and wherein each ofthe securing elements includes a through bore, through which the headscrew passes, and an engagement portion that extends within the grooveof the bulge.
 16. The universal joint according to claim 4 characterizedin that each of the securing elements includes a through bore, throughwhich the retaining trunnion extends, and wherein each of the securingelements is retained on the retaining trunnion by a securing ring thatextends within the circumferential groove of the retaining trunnion andwithin the groove of the bulge.
 17. The universal joint according toclaim 1 characterized in that each of the securing elements includes anarc portion that forms an arc-like engagement portion that extendswithin the groove of the bulge formed as a circular arc groove, at leastone retaining portion that extends within the circumferential groove ofthe retaining trunnion, and at least one connection portion thatconnects the at least one retaining portion to the arc portion.
 18. Theuniversal joint according to claim 17 characterized in that each of thearc portions and each of the at least one retaining portions arearranged in one plane or in planes offset to each other, and further arearranged distanced to each other and are elastically deformable towardseach other.
 19. The universal joint according to claim 17 characterizedin that one continuous retaining portion is provided so that the arcportion, the connection portions, and the retaining portion arecontinuous with each other.
 20. The universal joint according to claim19 characterized in that the retaining portion and the arc portion are,respectively, provided with an eyelet for engagement by a tool.
 21. Theuniversal joint according to claim 17 having a securing element with tworetaining portions, wherein an eyelet for the engagement of a tool isprovided on free ends of each of the retaining portions.